1. Field of the Invention
This invention relates to a ring-packed pipe spigot-and-socket connection in which an elastic packing ring, the cross section of which essentially has a V-shape, is located in an annular groove provided in the inside wall of a socket.
2. Brief Description of the Prior Art
A ring-packed pipe spigot-and-socket connection of this type is known from West German Patent Document No. 26 14 575 C3. In axial profile, the annular groove provided in the inside wall of the socket essentially has the shape of an irregular trapezoid with a steeper holding slope located at the rear in the direction of insertion of the front end of the spigot into the socket and with a flatter insertion slope located at the front in the direction of insertion of the spigot end into the socket. The insertion slope forms an angle of less than or equal to 30.degree. with the inside wall of the socket, while the holding slope forms an angle of more than or equal to 60.degree. with the inside wall of the socket. The elastic packing ring, which essentially is V-shaped, and the annular groove in the inside wall of the socket are coordinated with each other in such a way that when the packing ring has been inserted into the annular groove as specified, then the foot or lower segment of the packing ring rests against or is located only a slight distance removed from the holding slope of the annular groove, inside of the annular groove, below the inside wall surface of the socket. When the spigot end is being inserted, its front end encounters the front face of the leg of the ring projecting radially inward into the interior of the socket and, during the course of the continued insertion process, deflects this leg into the direction of insertion. This causes the outside edge of the foot or lower segment of the packing ring to slide downward on the holding slope of the annular groove to the bottom of the annular groove. At the same time, the leg of the packing ring pointing toward the socket outlet is lifted from the insertion slope and tilted radially inward until its radially extending inner surface fits against the outer wall of the spigot end.
What is functionally not quite satisfactory in the case of this known pipe spigot-and-socket connection is the shape of the profile of the annular groove and the manner in which the foot segment of the packing ring slides down the holding slope to the bottom of the annular groove when the spigot end is being inserted into the socket. Especially in the case of a narrow sealing clearance between the inside wall of the socket and the outside wall of the spigot end, it is possible for the packing ring to be lifted out or pulled out over the edge formed between the holding slope and the inside wall of the socket. Due to this, at least the contact pressure of the foot segment of the packing ring on the bottom of the annular groove is diminished. In extreme cases, it is even possible that the foot segment is lifted from the bottom of the annular groove. This phenomenon leads to a decrease in the reliability of the seal between the packing ring and the inside wall of the socket; more specifically, this leads to a decrease in the reliability of the seal between the foot segment of the packing ring and the bottom of the annular groove in the socket wall.